Method and apparatus for the production of carbon black



1)@.1s,1945. A P.-H. MITCHELL 2,391,067

METHOD AND APPARATUS FOR OOOOOOOOOOOOOOOOOOOOOOOO GK a 1% g r n, a W X 1f N 3 ":i A r/ R: 1/; 4%? a W W Dec. 18, 1945. PIH. MITCHELL 2,391,067

METHOD AND APPARATUS FOR THE PRODUCTION OF CARBON BL CK Filed Jan. 8,1942 2 Sheets-Sheet 2 A" is a i7 I? 'Inrenfor Patented Dec. 18, 1945UNITED. STATES: PATENT OFFICE METHOD AND APPARATUS FOR THE PRO-DUCTIONQF CARBON BLACK Percival H. Mitchellf' l oronto, Ontario, Canada,assignor to Albert Carson Ransom, Toronto,

Ontario, Canada Application January 8, 1942, Serial No. 425,977

(Cl. 23-2093) v nozzle bars for directing hydrocarbon into the 12Claims.

The principal objects of this invention are to j produce by dissociationfrom gaseous or vaportion zones to effect the maximum decomposition 1 ofthe hydrocarbon in forming carbon blackand to prevent contact of thematerial being decomposed with the furnace walls, and further, toutilize the heat produced in the combustion zones in providing andmaintaining boundaries for said combustion zones emanating radiant heatto assist in the dissociation action upon the stream of gaseous orvaporous hydrocarbon embraced by said heat zones.

A further important feature of the invention consists in the provisionof means for separating the central how of the hydrocarbon undergoingdissociation from products of combustion of the combustion zones ateither side thereof and directing the products of combustion soseparated into paths or zones to effect a heat exchange to wallsconfining said combustion zones and to direct the radiant energyabsorbed therefrom to amplify the heat applied in the dissociationprocess.

In the accompanying drawings Figure l is a diagrammatic illustration ofan apparatus constructed in accordance with the present inven-- tion tocarry out the novel process.

Figure 2 is an enlarged vertical mid-sectional view through the furnaceportion of the structure illustrated in Figure 1.

Figure 3 is a vertical cross section through the furnace taken on theline 33 of Figure 2.

Figure 4 is a horizontal sectional view taken through the line 1-4 ofFigure 2.

Figure 5 is an enlarged horizontal section through the furnacestructure. a

Figure 6 is an enlarged sectional detail of a portion of one of thenozzle bars for directing air or gas into the furnace.

Figure 7 is a cross sectional view through one of the nozzle bars.

Figure 8 is a cross section through one of the combustion zone of thefurnace.

Figure 9 is a horizontal sectional view of a modified form of furnaceand cooling chamber with a plurality of disassociation chambers therein.

Carbon black. is a commercial commodityrequired in various industries inextremely large quantities and it is found in practise that the productproduced by heat of dissociation varies considerably.

This invention has been demonstrated to have produced a densely blacksoft carbon and it is found that the apparatus devised can be con- 5trolled so that the yield of carbon of the desired quality is high.

On reference to the accompanying drawings, the furnace l is here shownas of a horizontal type and is of generally rectangular formbutpreferably long and narrow and extending longitudinally thereof and in avertical plane is a rectangular chamber 2. At either side of the chamber2 the side walls 3 are formed with longitudinal passages l which lead topassages 5 at one end communicating with a flue chamber 6 arranged abovethe top of the furnace adjacent to its front end.

The partition wall 1 between the central chamber 4 and the side chambers4 is preferably formed of refractory brick and the back ends 8 of theseare rounded. The outward walls of the passages 4 are curved inwardly andspaced from the rounded ends 8 of the partition I a distancesubstantially equal to the width of the passages 4 and said inwardlyrounded walls extend into the chamber 2 and past the outer wallsthereof, forming projecting lips 9 arranged either side of a centralpassage In which forms the exit for the, hydrocarbon gases or vapourthat has been subiect to dissociation within the main chamber 2.

At the end of the furnace opposite the exit opening Hi there is arrangeda plurality of nozzles. These nozzles are preferably in the form of barsll of rectangular .cross section preferably of suitable steel orrefractory material which are perforated by a plurality of, horizontalholes I2 which are preferably equally spaced throughout the length ofthe bar and extend from the outward to the inward side. bars l3, asshown in detail in Figure 5, have the nozzle orifices i2 arranged inparallel pairs and the said orifices are substantially parallel to theinner side walls of the furnace chamber 2.

Each of the bars I3 is installed in one side of The outer pair of avertical casing M .which forms an air chest being acted upon by heat todissociate and air directed into this chest flows the full length of theheight of the furnace and enters the chamber 2 through the multiplicityof air slightly outward and they project jets of gaseous fuel angularlyoutward toward the inner side walls of the furnace to mingle with theair projected through the nozzles of the bars II.

Each of the casings II is connected with a suitable gaseous or vaporousfuel supply. Centrally between the casings i5 is arranged a casing l8which is connected with a suitable supply of gaseous or vaporoushydrocarbon capable of ments and form carbon black. a

A nozzle bar I! is arranged at the inward side of the casing is and itis perforated with nozzle openings 20 arranged horizontally and spacedsubstantially equidistant throughout the length of the bar, said nozzleopenings being adapted to project jets of the gaseous or vaporoushydrocarbon axially into the furnace chamber 2 in a centralizedverticalplane.

The supply conduits leading to the nozzle casings Is and n are providedwith suitable control valves.

The air supply casings ll leading to the air nozzles are connected byconduits 2i controlled by suitable valves with an air heater 2! which isheated by the products of combustion drawn from the flue passages I andI connected with the passages l by means of a suitable exhaust fan 23.

In the operation of a furnace such as'described a supply of gaseous orvaporous fuel is directed into the furnace chamber 2 through the nozzlebars II which, as has been explained, are angularly directed outwardlytowards the inner walls of the furnace chamber 2. Concurrently with itselewalls of the furnace to and around the ends of the partition walls Iand into the passages l, maintains on ither side of the furnace ndistinct heating zone of combustion. The hydrocarbons projected into thecentral zone between these two combustion heating zones is not mixedwith air and is therefore practically of an incombustible nature butthis central stratum of hydrocarbon being enclosed on both sides byburning fuel is decomposed in such a manner as to liberate free carbonand the carbon black is formed.

The temperatures may be of course carefully controlled by themanipulation of the supply of fuel and air but these may be regulated inaccordance with the indications of a suitable thermocouple 24' whichprojects into the interior of I the chamber 2 through the furnace wall.

The heating operation is carried out slowly until the thermocouplethermometer registers a desired stabilized temperature, generallysomewhere bet n 1900' F. and 2300"v 1".

a 'After the urnace has been brought up to the desired workingtemperature the adjustments for the production of carbon black areproceeded with. The usual procedure is that the gas and air supplynozzles are regulated along with the exhaust fan draught to obtain apredetermined setting to maintain furnace temperatures during carbonproduction, it being desirable to adjust the proportion of gas and airso that enough or slightly less air than required for combustion of thegas is maintained. When this adjustment of temperature regulation hasbeen achieved the central sheet of hydrocarbon to be dissociated by theaction of heat is projected through the cendirecting this combustiblegas supply into the furnace chamber a desired quantity of air isdirected through the nozzle openings If, the air and gaseous or vaporousfuel mixing to form a combustible mixture and they are suitably ignited.

The exhaust fan connected withthe flue passages 6; 5 and 4, create adefinite circulation along the inner walls of the furnace and outthrough the passages I. The heat of the burning:

fuel and air is imparted to the dividing walls 1 between the chamber 2and the passages 4 and the heat of combustion flowing around the outwardside of these dividing walls raises these walls to a state ofincandescence. The outer walls of course absorb a certain quantity ofheat but they may be suitably insulatedor. formed of refractory andinsulating material so'as to prevent the unnecessary escapeof heat.

when the'furnace has been raised to a predetermined temperature a supplyof gaseous or vaporous hydrocarbon is directed in a vertical sheet intothe axial zone of the furnace through the nozzle openings 20 in the bar[8.

The admixture of the heating fuel directed through the nozzles l1 andthe air directed through the nozzles I3 is continued and theestablishment of a direct draught along the inner tral nozzle and thevolume is gradually increased preferably concurrently with the buildingup of fan draught on the exit.

It will be understood that there will be a wide 'range of adjustmentcapable of the amount of air, combustible hydrocarbon and of thedissociation hydrocarbon, which, along with variation in draughtpressures, may be regulated to meet the specific predetermined settingsfor continuous operation.

As has been described the outer furnace walls curve inwardl in spacedrelation to the terminal vertical edges of the walls 1 between thecombustion chamber and the flue passages l and the lip portions 9, whichproject inwardly past the inner walls, forming a discharge passage ll,narrower than the width of the main chamber 2. These lipsintercept theouter strata of the material flowing longitudinally of the furnacechamber 2 and experience and practical experiments have shown that alarge portion of the products of combustion of the outer strata areseparated from the central stratum of material dissociated by theapplication of heat.

The two reactions of combustion and dissociation are carried out'inadjacent planes with intermediate planes of mixed reaction. Theproportions of gas allotted for combustion and dissociation may varyapproximately from 40% to 60% or 60% to 40%, according to the type ofcarbon which it is desired to be produced. The hydrogen gas and carbonfrom dissociation ilows through the central exit opening II, which ispreferably widened at the entrance i0 and these products flow into asuitable cooling chamber 24 in which the temperature is reduced toapproximately 450 F. and from thence the carbon and itsassociated gasesflow into a precipitating chamber 25 which may be of a suitable formusing high tension electrical precipitation or ag lomeration.

The discharge from the precipitator is carried through a conduit 26under the influence'of an exhaust fan 21 audit is then directed into asuitable type of separator 21', herein illustratedv form, an example ofwhich is illustrated in rag-1,,

ure 9 which shows a pair of combustion and dissociation chambers 2'parallelly arranged each having double diversion passages 4' for theproducts of combustion leading to exit flues 5' which may be coupled ina suitable header controlled by a single exhaust fan. In this form theseparate exits Ill are connected to passages leading to a commonv exit29 which leads to the cooler 24 provided with a suitable dischargeleading to a precipitator Or an agglomerator, an exhaust fan and aseparator.

The invention is herein shown and described as applied to a horizontalflow but it will be understood that furnaces may be constructed with thenow arranged vertically and the combustion and separating chambers maybe of a rectangular flat type or they may be constructed in cylindricalform. In fact many cross sectional designs of furnace may be constructedwithin the scope of this invention so long as the principle ismaintained of directing a flow of hydrocarbon to be dissociated by heatin a centralized area embraced by zones of combustion and having bamingmeans for diverting a flow of products of combustion from the flow ofdissociated mate- -rial and passagesto conduct products of 00mbustion incontact with areas of the furnace walls outside of the dissociationchamber to effect the heating of said walls with the dischargingproducts of combustion and to efiect the dissemination of radiant heatinwardly from said walls to the dissociation chamber.

In furnaces of the types herein described the heat of combustion isutiilzed most efllciently in maintaining a high temperature in thereaction zone and there will be less heat loss through absorption by theouter walls of the furnace and the radiant heat of the inner walls actsdirectly in maintaining a uniform combustion in the combustion zone,thereby augmenting the heat for endothermic reaction and ensuringagreater yield of carbon from the hydrocarbon directed through thecentral zone.

It is obvious that the flow of combustion gases intervening between theradiant solid walls of the furnace and the dissociation zone, protectsthe gases in their dissociation reaction from being detrimentallyaifectedby contact with the solid radiant wall surfaces, a conditionwhich is desirable for many classifications of carbon black.

What I claim as my invention is: 1

l. A method of making carbonblack consistcarbon black, and separatingstreams of burning hydrocarbon from the outward sides of the main flowof the dissociation products at the discharge end of the combustionchamber.

2. A method of making carbon black consisting in creating within acombustion chamber spaced streams or burning hydrocarbon, concurrentlydirecting a flow of gaseous hydrocarbon between and in contact with saidburning streams and effecting dissociation of said gaseous hydrocarbonto produce carbon black, dividing a portion of the outward streams ofburning hydrocarbon from the cent-i'al stream of dissociation productsat the'di'schar'ge end of the combustion chamber and directing thedivided combustion products to form heated zones spaced from butsubstantially parallel with the burning hydrocarbon streams to minimizeloss in the heat of combustlon in dissociation of the gaseoushydrocarbon directed between the burning streams, and discharging thecentral stream of dissociation products from said combustion chamber.

3. A method of making carbon black consisting in creating within acombustion chamber substantially enveloping parallel burning streams ofhydrocarbon of a degree of heat suflicient to effect decomposition of agaseous hydrocarbon to form carbon black, directing a stream of suchgaseous hydrocarbon centrally between and in contact with ,saidburningstreams directly toward and through a discharge orifice, separatingproducts of combustion of the outward buming hydrocarbon streams fromthe enveloped stream of decomposed gaseous hydrocarbon at pointsadjacent to the discharge orifice, and discharging the combustionproducts separately from said combustion chamber.

4. A method of making carbon black consisting in directing streams ofoxygen containing gaseons-combustible substance adjacent to the innersides of the boundary walls of a combustion chamber, igniting saidcombustible mixture to form primary heating zones, diverting the flow ofsaid burning streams and directing same along the outer sides of thecombustion chamber boundary walls to form secondary heat zones,controlling the velocity flow of said burning streams, directing astream of hydrocarbon gas into said combustion chamber between and incontact with the burning streams and effecting decomposition of said gasand the formation of carbon black, and continuing the flow of thedecomposed hydrocarbon past the point of diversion of the bumingstreams; I

5. A method of making carbon black consisting in directing streams ofair into a combustionchamber substantially parallel to the inner wallsing in creating within a combustionchamber thereof. directing streams ofa combustible gas .angularly toward such walls and to mingle with saidair streams to form a combustible mixture flowing along the walls,igniting the'mixture, directing streams of hydrocarbon gas in a planecentrally between the said ignited streams directly toward a dischargpassage and efiecting decomposition of said gas by the heat of theburning strata either side thereof, and discharging the central strataof decomposed gas separately from the products of combustion of theouter combustible streams.

6. An apparatus for forming carbon black,

comprising a furnace having its side walls formed of the furnace fordiverting products of combus-' tion into the ends of said flue passagesopening into said combustion chamber a discharge outlet from saidcombustion chamber spaced between 7 said diverting means, and nozzleorifices at, the

end of the furnace opposite to said discharge out-' let for directing aflow of hydrocarbon gas through said combustion chamber in contact withsaid streams of combustible gas.

7. An apparatus for forming carbon black comprising a furnace having acombustion chamber and a discharge opening arranged centrally of one endthereof of lesser width than the interior of said chamber, flue passagesarranged within the walls of said furnace and openingto the combustionchamber on either side of said discharge opening and extendinglongitudinally within the side walls and away from said dischargeopening, nozzle openings arranged at the end of the combustion chamberopposite to the discharge opening adapted to direct streams ofcombustible gas'along the inner face of the side walls of saidcombustion chamber and toward the ends of the flue passages openingthereinto, and nozzle openings arranged between the aforesaid nozzleopenings and directing a flow of hydrocarbon gas longitudinally of saidcombustion chamber toward said discharge opening and between saidcombustible streams.

8. An apparatus for forming carbon black comprising a furnace havinglongitudinal side walls and end walls enclosing a horizontal combustionchamber, a vertically disposed discharge passage of lesser width thansaid combustion chamber arranged centrally of one end of said furnaceand leading from the combustion chamber, vertically disposed fluepassages arranged within the longitudinal side walls of the furnacehaving ends curving inwardly and opening into the combustion chamber ateither side ofsaid discharge passage, a plurality of nozzle openingsarranged at the end of the furnace opposite to the openings to said fluepassages and adapted to direct streams of combustible gas along theinner faces of the side walls of the combustion chamber, and a pluralityof nozzle openings adapted to direct streams of hydrocarbon gas throughsaid combustion chamber toward said centrally arranged discharge openingand between the streams of combustible gas.

9. An apparatus as claimed in claim 6 including exhaust means arrangedbeyond said discharge outlet for inducing the flow of the products ofdecomposition, and exhaust means connected with said flue passages inthe side walls of the furnace for inducting a regulated flow of productsof combustion from said furnace.

10. An apparatus as claimedin claim 6, including .a cooling chamberconnected with said central discharge outlet, a precipitator receivingthe cooled products from said cooling chamber, an exhaust fan connectedwith said precipitator, a separator beyond the exhaust fan to separatethe carbon from the gases, and an exhaust fan ccLoligected with saidflue passages in the furnace w 11. An' apparatus for forming carbonblack comprising a furnace having flat side walls, flue passages leadingfrom one end of the furnace longitudinally through said side walls, adischarge outlet at one end of the furnace arranged between the entrsnceto said flue passages and adapted to discharge the decompositionproducts from the furnace, and bars arranged in the end of the furnaceopposite said discharge, and flue passages each having a multiplicity ofholes therethrough forming nozzle openings to direct gases into thefurnace.

12. An apparatus for forming carbon black comprising a rectangularfurnace having flue openings at either side of one end leading from thecombustion chamber through the walls thereof,'a discharge openingleading from said combustion chamber arranged midway between said flueopenings to receive products of decomposition, vertically disposed barsarranged adjacent the side walls of said furnace and extending theheight of the furnace at the end of the combustion chamber opposite saiddischarge opening and each having a multiplicity of nozzle openingstherethrough in substantially parallel arrangement with the side wallsof the furnace to direct a multiplicity ofstreams of air along the innersurface of said walls, vertically disposed bars arranged adjacent to theaforesaid bars and each having a multiplicity of nozzle openingstherethrough directed outwardly to- PERCIVAL H. MITCHELL.

